N = int(input())
lista = list(map(int,input().split()))
#N = 15
#lista = [4,2,3,1,5,6,7,8,11,12,9,13,10,14,15]
#lista = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
#elter = [3,0,0,3,0,0,0,0,2,2,2,1,3,0,0]
maxelter = 0
maxelterpoz = []
maxertek = 0
for i in range(N):
    if abs(lista[i] - (i+1)) >= maxelter and lista[i] != i+1:
        if abs(lista[i] - (i+1)) > maxelter:
            maxelterpoz = []
            maxelter = abs(lista[i] - (i+1))
        maxelterpoz.append(i+1)          
#print(maxelterpoz)
if maxelter == 0:
    print(-1)
else:
    maxertek = 0
    for x in maxelterpoz:
        if lista[x-1] > x:
            minelterpoz = N
            for i in range(N-1,-1,-1):
                if lista[i] < lista[x-1]:
                    minelterpoz = i+1
                    break
            #print(x,minelterpoz)
            if minelterpoz - x > maxertek:
                maxertek = minelterpoz - x
                vegemin = x
                vegemax = minelterpoz
        else:
            minelterpoz = 1
            for i in range(N):
                if lista[i] > lista[x-1]:
                    minelterpoz = i+1
                    break
            #print(minelterpoz,x)
            if x - minelterpoz > maxertek:
                maxertek = x - minelterpoz
                vegemin = minelterpoz
                vegemax = x
    print(vegemin,vegemax)